The explanatory value of some post-connectionist models PowerPoint PPT Presentation

The explanatory value of some post-connectionist models. Jason Noble, Eric Silverman and Manuel de Pinedo University of Southampton Universidad de Granada. Where we’re coming from. Two out of three of us are not professional philosophers Our work is in: Cognitive science

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The explanatory value of some post-connectionist models

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Response to the challenge?

Question evaded more than answered: no systematic architectures built using 1980s connectionism

Post-connectionist movement (PCM) emerges:

Enactivism

Behaviour-based AI

Embodied and distributed cognition

Dynamical systems theory

PCM shares anti-dualist and anti-representational themes; unclear whether it gets around the challenge

What were F&P really saying?

That connectionism should be “relegated” to understanding some low-level aspects of cognition

That the language-of-thought hypothesis is the right level of description for cognition (?)

Understandable resistance to the “explanatory imperialism” of the connectionists: you can’t explain everything about thought by talking only about nodes and weights

Excessive explanatory ambition?

Consider psychology (P) and sociology (S).

P theorists might claim that unless S theorists can show a bridging explanation from P to S, then S is not a legitimate level of description.

S theorists might say much the same: unless P can show how their low-level entities give rise to the phenomena of S, then P is not to be taken seriously.

Few would argue this way in the P/S case: why does it seem more acceptable in cognitive science?

Is systematicity the real issue?

Clearly it’s a phenomenon of great interest to cognitive science that people possess concepts, reasoning, propositional logic, productivity, systematicity, etc. (or at least do a good impression of such).

It’s also reasonable to point out that the substrate that supports all this is neurological, chemical, and ultimately physical.

However: the strength of the current debate seems to rest on an assumption that one or the other form of explanation must win out.

An illustration from ALife

What’s the practical alternative to a battle between mutually exclusive paradigms?

Artificial life is a helpful source of examples here.

Focus on emergence: showing how a higher-level description of a system can emerge from interactions between simpler, lower-level components.

Two interpretations

Note the similarity with some of Randy Beer’s work on understanding evolved agents using dynamical systems theory.

Our main argument against such an approach is simply that it does not seem to scale very well in practice.

Two interpretations

A second way to read Quinn’s results is in terms of providing a bridging explanation between levels of description.

Quinn has shown that a Shannon-type signalling channel can evolve/emerge from lower-level interactions between agents.

This licences further modelling and theorizing at the level of signalling systems.

Not every ALife model needs to start with a primordial soup!

A call for humility

Mentioned earlier that no systematic connectionist architectures have been constructed.

On the other hand, it should be noted that practical language-of-thought architectures, such as Lenat’s CYC project, have also run into difficulties.

What to make of this?

We have argued elsewhere for explanatory pluralism in cognitive science.

A call for humility

We note the success of Tinbergen’s account of four different explanatory modes in biology:

Mechanism

Function (adaptive value)

Ontogeny

Phylogeny

None of these is to be reduced to the others; complete understanding in biology is a patchwork of all four.

Envisage a mature cognitive science as being similar.

A call for humility

There is a tendency to think that behind every empirical question is a philosophical question

This can lead to a one-size-fits-all approach to explanation that is not in the service of the empirical project, and is philosophically problematic

Questions for discussion

Ours is a very pragmatic, Wittgensteinian position: do the empirical and modelling work, and see which explanations turn out to be useful. What kinds of contributions do we leave room for from philosophy of mind?

What if bridging explanations don’t seem to be possible, e.g., anomalous monism?

What are the implicit metaphysics of our position?

Ryle/Ludwig rejecting both the ghost and the machine (M)

Contrast Marr and Gibson: G was not a lazy version of M (E)

History of the Fodorian challenge

Explanatory fascism in cognitive science

Introduction/description of Quinn's model

Explanatory pluralism in cognitive science

Bridging explanations/supervenience

Two ways to interpret Quinn's message

Wittgensteinian/Rylean metaphysics?

In L1/L2 cases, neither side uniquely responsible for bridging

Enthusiasm for new paradigms to explain all

Laboratory rather than armchair

Systematicity in the brain? Ridiculous

Context: philosophy of mind as part of the empirical cognitive science project

Troublesome tendency to think: behind every empirical question is a philosophy question

This can lead to a one-size-fits-all approach to explanation that is*not* in service of the empirical project - and is philosophically problematic